Non-film-forming electrophoretic latexes in fluorocarbon solvents

ABSTRACT

The present invention provides a non-film-forming latex of dispersed particles which may be used in an electrophoretic display, comprising: a) a highly fluorinated liquid solvent, and b) dispersed particles comprising a polymer comprising units according to formula I:                    
     wherein each (fcp) is independently selected from highly fluorinated polymer chains and each Q is independently selected from —H and straight or branched non-fluorinated polymer chains (hcp). Latexes of dispersed particles having a very small particle size are especially provided.

FIELD OF THE INVENTION

This invention relates to a latex of dispersed particles which may beused in an electrophoretic display. The latex is non-film-forming sothat the particles may be repeatedly removed from dispersion andredispersed. The latex comprises: a) a highly fluorinated liquidsolvent, and b) dispersed particles as specified herein.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 5,397,669 (Minnesota Mining & Manufacturing) disclosesliquid toners for use with perfluorinated solvents. The patent disclosesthat the compositions are film-forming, allowing them to functionproperly as toners. ('669 at p. 8 Ins. 3-5). The '669 patent disclosespigment particles bound to a polymer that is highly fluorinated inspecific parts, and that includes monomer units having groups that bindpolyvalent metal ions. The '669 patent also discloses pigment particlesbound to a polymer that is highly fluorinated in its entirety, withoutrequiring monomers having groups that bind polyvalent metal ions.

U.S. Pat. No. 5,530,053 (Minnesota Mining & Manufacturing) alsodiscloses liquid toners for use with perfluorinated solvents. The tonersof '053 are polymeric dyes which are highly fluorinated in specifiedparts and have attached chromophoric groups. The '053 patent disclosesthat the toner can form a latex in perfluorinated solvent, where thetoner takes a core-shell form with the hydrocarbon portion in the coreand the fluorocarbon portion in the shell.

U.S. Pat. No. 5,919,293 (Hewlett-Packard) discloses ink jet inkscomposed of colorants in Fluorinert™ solvents (Minnesota Mining &Manufacturing Co., St. Paul, Minn.), which are perfluorinated ornearly-perfluorinated alkanes.

U.S. Pat. No. 5,573,711 (Copytele) discloses the use of certainpolymeric fluorosurfactants in electrophoretic image displays. The '711patent teaches the use of Fluorad™ surfactants (Minnesota Mining &Manufacturing Co., St. Paul, Minn.), including FC-171, having thestructure R_(f)—SO₂N (C₂H₅)(CH₂CH₂O)_(n)CH₃, where n is about 8 andR_(f) is a fluorocarbon portion.

SUMMARY OF THE INVENTION

Briefly, the present invention provides a non-film-forming latexcomprising a highly fluorinated liquid solvent and dispersed particlescomprising a polymer comprising units according to formula I:

wherein each (fcp) is independently selected from highly fluorinatedpolymer chains which may terminate at the —A═ group of another unitaccording to formula I so as to form a polymer molecule that containstwo or more A groups linked by (fcp) groups; wherein each Q isindependently selected from —H and straight or branched non-fluorinatedpolymer chains (hcp), wherein no more than one Q of each unit accordingto formula I may be —H, and wherein each (hcp) may terminate at the —A═group of another unit according to formula I so as to form a polymermolecule that contains two or more A groups linked by (hcp) groups. The—A═ group may be the moiety according to formula II:

wherein each R¹ is independently selected from —H, —CH₃, —F and —Cl;wherein each —R⁶— is independently selected from divalent substituted orunsubstituted C1-C10 cyclic alkylene, or arylene groups. The (hcp)groups may be branched where polyfunctional crosslinkers are included.The (hcp) groups may contain reacting dyes as monomer units in thepolymer chain. The particles may additionally contain non-reacting dyes.The particles may additionally contain charging agents.

In another aspect, the present invention provides a non-film-forminglatex comprising a highly fluorinated liquid solvent and dispersedparticles comprising a polymer which is the polymerization product of amixture comprising: i) 40-99 percent by weight of one or morenon-fluorinated free-radically-polymerizable monomers, ii) 1-60 percentby weight of one or more highly fluorinated macromers terminated at oneor more sites with free-radically-polymerizable groups, iii) 0-35percent by weight of one or more crosslinkers having two or morefree-radically-polymerizable groups, and iv) 0-25 percent by weight ofone or more reacting dyes bearing a free-radically-polymerizable group.The particles may additionally contain non-reacting dyes. The particlesmay additionally contain charging agents.

In another aspect, the present invention provides an electrophoreticdisplay comprising the non-film-forming latex herein, wherein saiddispersed particles may be alternately a) removed from dispersion byapplication of an electric field, and b) redispersed by removal orreversal of said electric field.

What has not been described in the art, and is provided by the presentinvention, is a non-film-forming latex of hydrocarbon/fluorocarbonparticles dispersed in a fluorocarbon solvent useful in anelectrophoretic display, and more specifically a latex having the smallparticle size and high conductance disclosed herein.

In this application:

“reacting dyes” means dyes which are covalently bound to the polymer;

“non-reacting dyes” means dyes which are not substantially incorporatedinto a polymer by polymerization, including every dye that is not areacting dye;

“highly fluorinated”, means containing fluorine in an amount of 40 wt %or more, but preferably 50 wt % or more and more preferably 60 wt % ormore, and refers to the fluorine content of a population of chemicalmoieties where applicable, such as in the term, “one or more highlyfluorinated macromers”;

“non-fluorinated”, means containing substantially no fluorine, i.e.containing fluorine in an amount of 5 wt % or less, but preferably 1 wt% or less and most preferably 0 wt %, and refers to the fluorine contentof a population of chemical moieties where applicable, such as in theterm, “one or more non-fluorinated free-radically-polymerizablemonomers”;

“C(number)” refers to a chemical moiety containing the indicated numberof carbon atoms;

“(meth)acrylate” means acrylate and methacrylate; and

“substituted” means, for a chemical species, substituted by conventionalsubstituents which do not interfere with the desired product or process,e.g., substituents can be alkyl, alkoxy, aryl, phenyl, halo (F, Cl, Br,I), cyano, etc.

It is an advantage of the present invention to provide a latex ofnon-film-forming dye-bearing particles, which latex is useful in anelectrophoretic display and can be used for repeated cycles ofelectrophoretically removing the particles of the latex from dispersionand returning them to dispersion.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides a non-film-forming latex comprising ahighly fluorinated liquid solvent and dispersed particles comprising apolymer comprising units according to formula I:

wherein each (fcp) is independently selected from highly fluorinatedpolymer chains which may terminate at the —A═ group of another unitaccording to formula I so as to form a polymer molecule that containstwo or more A groups linked by (fcp) groups; wherein each Q isindependently selected from —H and straight or branched non-fluorinatedpolymer chains (hcp), wherein no more than one Q of each unit accordingto formula I may be —H, and wherein each (hcp) may terminate at the —A═group of another unit according to formula I so as to form a polymermolecule that contains two or more A groups linked by (hcp) groups.Preferably some of the (hcp) groups are branched due to the inclusion ofpolyfunctional crosslinkers. Preferably the particles contain reactingor non-reacting dyes. Preferably the particles additionally containcharging agents.

Preferably the —A═ group is the moiety according to formula II:

wherein each R¹ is independently selected from —H, —CH₃, —F and —Cl;wherein each —R⁶— is independently selected from divalent substituted orunsubstituted C1-C10 alkylene, cyclic alkylene, or arylene groups. The(fcp) moieties may terminate at A groups at one or both ends. The (hcp)moieties may terminate at A groups at one or both ends, or at more thantwo ends if the (hcp) moiety is branched due to the inclusion of acrosslinker. Thus it is contemplated that a single molecule may containnumerous A groups linked by (hcp) groups.

The fluorocarbon polymer (fcp) portions are preferably highlyfluorinated macromers. Preferred macromers include macromers of monomersselected from fluoroalkyl acrylates, fluoroalkyl methacrylates,fluoroalkyl haloacrylates and fluoroalkyl halomethacrylates. Preferablythese macromers are fluoropolymer chains comprising units according toformula III:

where each R¹ is independently selected from —H, —CH₃, —F and —Cl; eachn is independently selected from integers from 1 to 10; and each R² isselected independently from: highly fluorinated substituted orunsubstituted C1-C20 alkyl, cyclic alkyl, or aryl groups; —N(R³)SO₂R⁴,where each —R³ is selected independently from —H and substituted orunsubstituted C1-C8 alkyl, and where each —R⁴ is selected independentlyfrom highly fluorinated substituted or unsubstituted C1-C20 alkyl,cyclic alkyl, or aryl groups. Preferably —R¹ groups are —H or —CH₃.Preferably n is 1 or 2, more preferably 1. Preferably —R² is a highlyfluorinated C1-C20 alkyl group, more preferably a highly fluorinatedC1-C8 alkyl group. In another preferred embodiment, the —R² groups ofthe (fcp) are a mixture selected from highly fluorinated C1-C8 alkylgroups and —N(R³)SO₂R⁴, where —R³ is selected from C1-C8 alkyl groups—R⁴ is selected from highly fluorinated C1-C8 alkyl groups.

In another preferred embodiment, (fcp) are polyfluoroalkylethers,preferably those comprising one or more units according to the formula—(CF₂)_(a)CFXO—, where a is 0-3, but most preferably 1, and X is —F,—CF₃ or —CF₂CF₃ but most preferably —F. More preferredpolyfluoroalykylethers comprise units according to the formula—CF₂CF₂O—. Preferred polyfluoroalykylethers are those according to theformula —NHCO₂(CH₂)_(p)(CF₂)_(q)—O—(CF₂CF₂O)_(m)(CF₂)_(r)(CH₂)_(s)OHwhen (fcp) is monovalent or—NHCO₂(CH₂)_(p)(CF₂)_(q)—O—(CF₂CF₂O)_(m)(CF₂)_(r)(CH₂)_(s)CO₂NH— when(fcp) is divalent, where p is 1-4, q is 1-5, r is 1-5, s is 1-4, m is1-50. Preferably p is 1-2. Preferably q is 1-2. Preferably r is 1-2.Preferably s is 1-2. Preferably p is equal to s and q is equal to r.Preferably m is 5-20 and more preferably 7-15. The chain may alternatelyterminate with —F in place of —(CH₂)_(s)OH in the formula above.

The hydrocarbon polymer (hcp) groups are preferably non-fluorinatedmacromers (including co-macromers) of (meth)acrylate and otherethylenically unsaturated monomers such as styrenes. The hydrocarbonpolymer (hcp) macromers are preferably polymers or copolymers of one ormore of the following preferred monomers. Preferred monomers includemonomers according to the formula: CH₂═CR¹—C(O)OR², where —R¹ ishydrogen or methyl and —R² is selected from C1-C20 substituted orunsubstituted, straight-chain or branched or cyclic, alkyl or arylgroups. Especially preferred monomers of this group include ethyl(meth)acrylate, methyl (meth)acrylate and isobornyl (meth)acrylate,butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate,hydroxypropyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate.Preferred monomers also include styrene or substituted styrene monomerssuch as methylstyrene.

The hydrocarbon polymer (hcp) portions preferably includenon-fluorinated crosslinkers, and are therefore branched. Preferredcrosslinkers include polyacrylates such as PEG Diacrylate with amolecular weight of preferably between 200 and 2000.

In order to improve resistance to film-forming, preferably the (hcp)portion of the particles contains one or more of: crosslinkers, cyclicor polycyclic monomers, aromatic monomers, and C12 or larger substitutedor unsubstituted alkyl monomers. More preferably the (hcp) portion ofthe particles contains one or more of: crosslinkers, cyclic orpolycyclic monomers and aromatic monomers.

The hydrocarbon polymer (hcp) portions may also include reacting dyeswhich are incorporated into the polymer chain as monomer units. Suchreacting dyes contain a chromogenic portion and a reactive portion,which are not exclusive of each other. Preferably the reactive portionis a free-radically-polymerizable group, such as a vinyl or(meth)acrylate group. In one preferred embodiment, afree-radically-polymerizable group is added to a dye by derivatizationwith isocyanatoethyl methacrylate. In one procedure, the dye issuspended in a solvent such as FC-75 by sonication and an equivalent ofisocyanatoethyl methacrylate is added dropwise, followed by two drops ofdibutyltin dilaurate catalyst and continued sonication and agitation for1 hour. A preferred reacting dye and method of preparation is disclosedin the examples below.

The dispersed particles may also include non-reacting dyes. Thenon-reacting dyes have greater affinity for the particles than for thesolvent and are therefore contained in the particles. Preferably thenon-reacting dyes have greater affinity for the (hcp) portions of theparticle than for the (fcp) portions or the solvent. Preferrednon-reacting dyes are disclosed in the examples below. The particlesaccording to the present invention preferably contain no particulatepigments.

Without wishing to be bound by theory, it is believed that the particlestake the form of a hydrocarbon-polymer-rich core and afluoropolymer-rich shell. It is believed that most dyes are incorporatedin the core due to compatibility with the hydrocarbon material of thecore. Thus it is believed that reducing the fluoropolymer content of theparticles improves the optical properties of the particle by allowingeasier access to the dyed core. In addition, it is believed thatreducing the fluoropolymer content of the particles can improve theparticle's resistance to film formation. Preferably the particles arecomposed of 40-99 percent by weight non-fluorinated hydrocarbon polymerand 1-60 percent by weight highly fluorinated fluoropolymer. Morepreferably the particles are composed of 60-99 percent by weightnon-fluorinated hydrocarbon polymer. More preferably the particles arecomposed of 1-40 percent by weight highly fluorinated fluoropolymer.Most preferably the particles are composed of 1-10 percent by weighthighly fluorinated fluoropolymer. However, greater fluoropolymer contentis acceptable as particle size is decreased. In particles of less than200 nm average diameter, the particles are preferably composed of 10-40percent by weight highly fluorinated fluoropolymer, more preferably10-25 percent by weight highly fluorinated fluoropolymer.

The dispersed particles may also include charging agents. The chargingagent renders the particle mobile under the influence of an electricfield. In addition, the charge imparted to the particles by the chargingagent creates an electrostatic repulsion between particles whichimproves resistance to film formation. Like non-reacting dyes, thecharging agent has a greater affinity for the particles than for thesolvent and is therefore contained in the particles. Preferably thecharging agent has a greater affinity for the (hcp) portions of theparticle than for the (fcp) portions or the solvent. The charging agentis preferably cationic, more preferably a quaternary ammonium cation.Preferred charging agents include 1-ethyl-3-methyl-1H-imidazoliumbis(trifluoromethylsulfonylamide), which may be prepared as disclosed inthe examples below; (C₄H₉)₃N:HOC(O)—C₇F₁₅; (C₃H₇)₄N⁺⁻OC(O)—C₇F₁₅;C₄H₉)₄N⁺⁻OC(O)—C₉F₁₉; C₇F₁₅—CO₂H; and combinations thereof.

Latexes according to the present invention preferably demonstrate a highconductance as measured by the method described in the examples below.Measured conductance is taken to reflect the charge/mass ratio (chargedensity) of the particles in suspension, whether imparted by thecharging agent or inherent in the particle itself. Preferred latexesaccording to the present invention have a conductance of 1 picomho/cm ormore, more preferably 4 picomho/cm or more, and most preferably 9picomho/cm or more. However, lower conductance is acceptable whenparticle size is decreased. In particles of less than 200 nm averagediameter, conductance is preferably 0.1 picomho/cm or more.

The average diameter (particle size) for the dispersed particles of thelatex is preferably measured by the method described in the examplesbelow. Smaller particles are preferred for a number of reasons,including greater and faster mobility and lesser tendency to form afilm. Preferably the particles have an average diameter of 1000 nm orless, more preferably 350 nm or less, more preferably 300 nm or less,more preferably 250 nm or less, and most preferably 200 nm or less. Theseed method of latex formation described below has been found to produceexceptionally fine particles. That method and the resulting fineparticles are preferred.

The solvent may be any suitable highly fluorinated solvent. The solventis preferably a fluorocarbon, especially a branched or unbranched,cyclic or non-cyclic fluoroalkane. Preferred solvents includeFLUORINERT™ fluorinated solvents available from 3M Company, St. Paul,Minn. Two especially preferred solvents are FLUORINERT FC-75, aperfluorinated C₈ solvent, CAS No. [86508-42-1], and FLUORINERT FC-84, aperfluorinated C₇ solvent, CAS No. [86508-42-1].

The density of particles in solvent (solids content) may be any level atwhich the dispersion is stable and does not significantly coagulate. Foruse of the latex in an electrophoretic display, the solids content maybe any level that allows proper functioning over repeated cycles.Preferably, the solids content is less than 10 wt %, more preferablyless than 5 wt %, and most preferably less than 2 wt %.

The latexes according to the present invention may be incorporated intoelectrophoretic displays. A typical display comprises two planarelectrodes defining a thin gap between them which holds the latex. Whena sufficient voltage of the correct polarity is applied, the suspendedparticles are drawn out of suspension and onto one electrode. Thatelectrode, which is substantially transparent, forms the inner surfaceof a viewing glass, such that the particles form an image viewed throughthe glass. In contradiction to the characteristics of an electrostatictoner, which must form a permanent image under analogous conditions, thelatex of the present invention must return to suspension when thevoltage is removed or reversed.

The latexes of the present invention have high resistance to filmformation when used in electrophoretic display devices. To determineresistance to film formation, an actual device may be used or abreadboard device as described in the examples below. Latexes of anysolids content may be tested but preferably the solids content is 1 wt%. The device is preferably used in a normal manner, alternatelyapplying and removing (or reversing) the typical use voltage. Thevoltage should be sufficient to remove particles from suspension andcreate an image when applied. Preferably the latexes arenon-film-forming to the extent that they redisperse completely (byappearance to the naked eye) after at least twenty cycles, morepreferably after at least 100 cycles, and most preferably after at least10,000 cycles. Without wishing to be bound by theory, it is believedthat the resistance to film formation demonstrated by the latexes of thepresent invention is aided by incorporation of crosslinkers, by thechoice of high Tg monomers such as 3,4 methyl styrene, isobornylacrylate, by reduction of the fluoropolymer content resulting in athinner outer shell zone, by increasing the electrostatic charge(conductance) of the particles, by exclusion of particulate pigments,which may be replaced with dyes. The latexes and particles according tothe present invention are preferably non-film-forming due to one or moreof the preceding conditions.

Any suitable method of synthesis which results in the latexes accordingto the present invention may be used. One method of making latexesaccording to the present invention is illustrated by the syntheses oflatexes L1 to L15 in the Examples below. In this method, a highlyfluorinated macromer is synthesized by polymerization and the macromeris then derivatized to add a terminal polymerizable group. The macromeris then polymerized together with non-fluorinated monomers, preferablyusing a polymerization initiator and optionally a crosslinker, to formthe latex particle. Reacting dyes must be added prior to polymerization.Non-reacting dyes and charging agents may be added at any stage, but arepreferably added prior to polymerization. All reactions preferably takeplace in a highly fluorinated solvent. Preferably the reaction mixtureis no more concentrated than 15 wt % reactants relative to the amount ofsolvent.

A more preferred method of making the latexes of the present inventionis designated the seed method, and is illustrated by the syntheses oflatexes L16 to L18 in the Examples below. In this method thepolymerization to form the latex particles is performed in two steps.First, the highly fluorinated macromer and a fraction of thenon-fluorinated monomers are polymerized with agitation to form apopulation of seed particles. The weight ratio of highly fluorinatedmacromer to non-fluorinated monomer is preferably between 1:2 and 9:1.In the second step, the remainder of the non-fluorinated monomers areadded. The amount of additional monomer is preferably at least 10% ofthe weight of the seed particles, and preferably not more than 20 timesthe weight of the seed particles. Preferably the reaction mixture is nomore concentrated than 15 wt % reactants relative to the amount ofsolvent. The seed method can achieve a smaller average particlediameter, preferably 250 nm or less, and more preferably 200 nm or less.

This invention is useful in electrophoretic image displays.

Objects and advantages of this invention are further illustrated by thefollowing examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this invention.

EXAMPLES

Materials

The following materials were used in these examples. Where not otherwisenoted, all chemicals and reagents may be available from Aldrich ChemicalCo., Milwaukee, Wis.

TRIGONOX™ 21C-50 (50%) is a trade designation for a thermal free radicalpolymerization initiator available from Akzo Nobel Chemicals, Inc.,Watertown, Conn.

FLUORINERT™ materials are fluorinated solvents available from 3MCompany, St. Paul, Minn. FLUORINERT FC-75 is a perfluorinated C₈solvent, CAS No. [86508-42-1]. FLUORINERT FC-84 is a perfluorinated C₇solvent, CAS No. [86508-42-1].

FLUORAD™ materials are fluorinated surfactants/surface modifiersavailable from 3M Company, St. Paul, Minn. FLUORAD FC-740 is 50%fluoroaliphatic polymeric esters in naphtha, CAS No. [64742-94-5].FLUORAD FC-171 is a mixture of 87-93% fluorinated alkylalkoxylate, CASno. [68958-61-2]; 4-10% fluorinated alkylsulfonamide, CAS no.[4151-50-2]; and 2-4% fluorinated alkylsulfonamide, CAS no.[68958-60-1]. FLUORAD FC-722 is a 2% solution of fluorinated copolymerin perfluorinated C₅₋₁₈ solvent, CAS No. [86508-42-1]. FLUORAD FC-430 isa 98.5% solution of fluoroaliphatic polymeric esters in toluene. FLUORADFC-189 is 2—(N-butylperfluorooctanesulfonamido)ethyl acrylate. FLUORADFC-170C is 68 wt % perfluoroalkylsulfonamido oxyethylene adduct[29117-08-6], 12 wt % polyethylene glycol, 7 wt % water, approx. 5 wt%.perfluoroalkylsulfonamido oxyethylene adduct [56372-23-7], and approx.5 wt. % perfluoroalkylsulfonamido oxyethylene adduct [68298-79-3].

Lithium bis(trifluoromethylsulfonyl)amide is available under the tradedesignation HQ-115 from 3M Company, St. Paul, Minn.

1H, 1H-perfluoroalkyl methacrylate is available under the tradedesignation L-1987 from 3M Company, St. Paul, Minn.

1H,1H-perfluorooctyl acrylate is available from Exfluor Corp., Austin,Tex.

PEG (400) diacrylate is a polyethylene glycol diacrylate available fromPolysciences, Inc., Los Angeles, Calif.

Dibutyltin dilaurate, isocyanatoethyl methacrylate, vinyltrifluoroacetate, 3-mercapto-1,2-propanediol,2,2′-azobis(isobutyronitrile), isobornyl methacrylate, methylmethacrylate, ethyl methacrylate, 1-ethyl-3-methyl-1H-imidazoliumchloride, 2,2,2-trifluoroethyl acrylate, and dimethylaminoethylmethacrylate are available from Aldrich Chemical Co., Milwaukee, Wis.and other general chemical suppliers.

Mercaptopropyltrimethoxysilane was obtained from United ChemicalTechnologies, Inc., Petrarch Systems, Bristol, Pa.

OXSOL™ R 2000 is α,α,α-trifluoromethyltoluene, available from OccidentalChemical Corp., Dallas, Tex.

FLUORAD™ FC-3275 is a blue dye in perfluorinated C₇-C₈ solventsavailable from 3M Company of St. Paul, Minn.

GENSOLVE™ 2000 is dichlorofluoromethane CAS No. 1717-00-6; also labeledas hydrochlorofluorocarbon HCFA-141b.

Synthesis of Fluoromacromer Solvents with Polymerizable Terminal Groups

Fluorocarbon macromers designated FMD-1, FMD-2, FMD-3 and FMD-4, weresynthesized using the components listed in Table I and the proceduredescribed following.

A mixture of the monomers indicated in Table I was dissolved in theindicated solvent (Fluorinert™ FC-75 or FC-84) to make a 50% (by weight)solution, in a three-neck flask equipped with a reflux condenser,nitrogen inlet tube and addition funnel. The specified amount of3-mercapto-1,2-propanediol was added as a chain transfer agent. Themixture was flushed with nitrogen for 20 minutes. The specified amountof the indicated polymerization initiator (Trigonox 21C-50 or2,2′-azobisisobutyronitrile) was added. The mixture was then polymerizedfor 12 hrs at 75° C. A second increment of the initiator in the sameamount was added and the mixture was polymerized for another 12 hrs at75° C. Next, the reaction temperature was raised to 85° C. for 1 hr todestroy residual initiator. The polymer dispersion was then cooled toroom temperature.

Finally, the terminal group monomer, isocyanatoethyl methacrylate (IEM),was added with thorough mixing in the indicated amount, which isstoichiometrically equimolar to the chain transfer agent, followed bytwo drops of dibutyltin dilaurate to complete the reaction of theisocyanate with one of the two hydroxyl end groups of the polymer.

TABLE I FMD-1 FMD-2 FMD-3 FMD-4 Fluorinert ™ Solvent FC-84 FC-84 FC-75FC-75 Monomers: 1H,1H-Perfluoroalkyl methacrylate 93.6 g1H,1H-Perfluorooctyl acrylate 136.23 g 136.23 g 136.23 FLUORAD ™ FC-18945.4 g 45.4 g 31.2 g Dimethylaminoethyl methacrylate 13.6 g Vinyltrifluoroacetate 25 g 2,2,2-trifluoroethyl acrylate 25 g Chain TransferAgent: 0.3225 g 0.3225 g 0.2 g 0.215 g 3-mercapto-1,2-propanediolInitiators: Trigonox ™ 21C-50 1 g 1 g 0.5 g 0.32 g2,2′-azobisisobutyronitrile 0.33 g Terminal Group Monomer: 0.925 g 0.925g 0.60 g 0.62 g Isocyanatoethyl methacrylate

Synthesis of Charging Agent, 1-Ethyl-3-methyl-1H-imidazoliumbis(trifluoromethylsulfonylamide)

1-Ethyl-3-methyl-1H-imidazolium chloride (49.0 g) was dissolved in 285.0g deionized water to form a 1M solution. 127.8 ml of this solution wascombined with 36.7 g lithium bis(trifluoromethylsulfonyl)amide and 50 mldichloromethane in a flask with a magnetic stir bar. The solution wasallowed to stir overnight, then transferred to a separatory funnel,where the aqueous phase was washed three times with 10 ml ofdichloromethane. The three dichloromethane phases were combined and thedichloromethane was removed under reduced pressure. The recoveredmaterial was used without further purification.

Synthesis of Non-Film Forming White Acrylic Latex Particles

White (non-dye-bearing) acrylic latexes, designated L1, L2, L3, L4 andL5, were synthesized using the components listed in Table II and theprocedure described following.

A mixture of the indicated acrylic monomers, optionally including PEG400 diacrylate crosslinker as indicated, was suspended in 500 ml ofFluorinert™ solvent FC-75 along with the indicated fluoromacromersolvent, FMD-1 or FMD-4, in a three-neck flask equipped with a refluxcondenser, nitrogen inlet tube and addition funnel. Where indicated, amixture of the indicated Fluorad™ surfactants was added to enhance thestability of the dispersion. Where indicated, a charging agent,1-ethyl-3-methyl-1H-imidazolium bis(trifluoromethylsulfonylamide), wasadded. A polymerization initiator, Trigonox™ 21C-50, was added in anamount of 0.1-0.2% by weight of the reaction mixture. This reactionmixture was flushed with nitrogen for 20 minutes and then the mixturewas polymerized for 12 hrs at 75° C. A second increment of the initiatorin the same amount was added and the mixture was polymerized for another12 hrs at 75° C. The resulting latex was then filtered through a thicklyfolded cheese cloth to remove agglomerated particles.

The resulting latexes contained a solids content of about 5 wt %. Solidscontent was measured by evaporating a known weight of the latex todryness by heating to 100° C. in a vacuum oven and weighing of theremaining dry solids.

Particle size and size distribution, reported in Table II, were measuredusing a Coulter N4 PLUS dynamic light scattering photometer (CoulterCorp., Miami, Fla.) with a measuring range of 3 nm to 3 μm. Particlesize and size distributions were obtained at the high dilution range setby the instrument.

Conductance, reported in Table II, was measured using a ScientificaModel 627 conductivity meter (available from Scientifica of Princeton,N.J.) using a stainless steel concentric cylinder probe. A frequency of18 Hz was applied to the outer cylinder. The conductivity of the liquidsample was determined by measuring the current between the outercylinder and the inner cylinder. Higher conductance is indicative ofhigher charge/mass ratio, which indicates that the particles may be moreeasily moved by application of an electric field.

Film-forming characteristics were tested in a breadboard display device,which included a transparent indium tin oxide electrode coated on anessentially planar high refractive index display glass opposite anessentially planar metal counter electrode. The gap between electrodeswas 5-10 μm. The volume between the display glass electrode and thecounter electrode was filled with the latex to be tested and a voltageof 10 volts was applied for less than a second, driving the latexparticles to the display glass. After the voltage was removed,non-film-forming latexes redispersed in the solvent, whereasfilm-forming latexes fully or partially remained on the display glass.Non-film-forming latexes redisperse completely (by appearance to thenaked eye) after at least twenty cycles. Film forming latexes typicallywould not rediperse in the first or second cycle. Toner compositions areunable to redisperse after a single cycle, consistent with their role inelectrophotographic processes.

Latexes L1-L5 were found to be non-film forming.

TABLE II L1 L2 L3 L4 L5 Monomers: Ethyl Methacrylate 20 g 15 g MethylMethacrylate 20 g 15 g Isobornyl Methacrylate 20 g 20 g PEG 400Diacrylate 4 g 4 g FC Macromer: FMD-4 12.5 g FMD-1 1.5 g 1.5 g 12.5 g 15g Surfactant Mixture: none none FC-430, 2 g FC-740, 0.6 g FC-430, 2.0 gFluorad ™ surfactants FC-170C, 3 g FC-171, 0.5 g FC-170C, 2.5 g FC-722,2.5 g Charging Agent: none none 0.5 g 0.5 g none Conductance 1.74 4.89.5 4.5 9.5 (picomho/cm) Particle Size 302 nm 575 nm 800 nm 280 nm notmeasured {distribution} {narrow} {broad} {broad} {narrow}

Addition of Charging Agent to Non-Film Forming Acrylic Latex ParticleDispersions

Acrylic latexes L1, L2, L4 and L5 were diluted to 1 wt % dispersions inFC-75 solvent. Additional charging agent was added to the dispersion inthe amount indicated and the conductivity was measured by the methoddescribed above.

TABLE III L1 L2 L4 L5 Conductance (picomho/cm) No additional chargingagent 1.74 4.8 4.6 9.5 0.02% additional charging agent 1.83 4.4 4.6 9.30.04% additional charging agent 1.85 4.3 4.7 9.2 0.10% additionalcharging agent 902 220 550 1398

Synthesis of Non-Film Forming Dye-Bearing Acrylic Latex Particles

Dye-bearing acrylic latexes, designated L6 (Cyan), L7 (Cyan), L8 (Red),L9 (Yellow), L10 (Yellow), L11 (Violet), L12 (Magenta), L13 (Cyan) andL14 (Magenta), were synthesized using the components listed in Table IVand the procedure described following.

A mixture of the indicated acrylic monomers, optionally including PEG400 diacrylate crosslinker as indicated, was suspended in 500 ml ofFluorinert™ solvent FC-75 along with 2.0 g of fluoromacromer solventFMD-1. (IBA=isobornyl acrylate, MMA=methyl methacrylate, EMA=ethylmethacrylate). For L6 (Cyan) only, 3 g of a mixture of Fluorad™surfactants (2:3 by weight FC-430 and FC-171) was added to enhance thestability of the dispersion. The indicated hydrocarbon-soluble dye wasdissolved in the monomer mixture along with a small quantity ofGenesolve™ 2000 (essentially CH₃CCl₂F; Allied Signal, Morristown, N.J.)to facilitate and accelerate the solvation of the dye. A polymerizationinitiator, Trigonox™ 21C-50, was added in an amount of 0.1-0.2% byweight of the reaction mixture. This reaction mixture was flushed withnitrogen for 20 minutes and then the mixture was polymerized for 12 hrsat 75° C. A second increment of the initiator in the same amount wasadded and the mixture was polymerized for another 12 hrs at 75° C. Theresulting latex was then filtered through a thickly folded cheese clothto remove agglomerated particles.

Dyes were modified as follows:

PECHS salts of Basic Violet (C.I. 42555) and Basic Blue (C.I. 1) weremade by exchanging cations for PECHS:

Derivatized Solvent Yellow 18 (C.I. 12740) was a reactive dyeincorporating a function polymerizable with the acrylic monomers. Thederivatized dye was made as follows: 1 g of Solvent Yellow 18 (C.I.12740) was suspended in ˜25 ml of FC-75 perfluorinated fluid bysonication. Isocyanatoethyl methacrylate (0.566 g ) was added dropwiseto the dye suspension under sonication, followed by two drops ofdibutyltin dilaurate catalyst. After an hour under sonication andagitation, the suspension was filtered, washed with FC-84 and driedunder vacuum below 40° F., the dry solid being the derivatized dye.

It was found that the dyes were substantially entirely contained in thelatex particles, presumably in the hydrocarbon polymer core. Unreacteddye was found in a coagulum obtained after filtering the latex throughcheesecloth as described.

The resulting latexes contained a solids content of about 5 wt %,measured as described above.

Particle size and conductance were measured as described above. LatexesL6-L14 were each tested and proved to be non-film forming.

TABLE IV L12 L14 L10 L6 (Cyan) L7 (Cyan) L11 (Violet) L13 (Cyan) L8(Red) (Magenta) (Magenta) L9 (Yellow) (Yellow) Dye 0.25 g 0.25 g 0.2 gBasic 0.2 g Basic 0.25 g 0.2 g 0.2 g 1.6 g 1.75 g Solvent Solvent VioletBlue (C.I. 1) Solvent Red Magenta Magenta Derivatized Derivatized Blue(C.I. 97) Blue (C.I. 97) (C.I. 42555) PECHS salt 23 (C.I. Solvent DyeSolvent Dye Solvent Solvent PECHS salt 26100) (CAS 58559- (CAS 58559-Yellow 18 Yellow 18 02-7) 02-7) (C.I. 12740) (C.I. 12740) Monomer 25 gMMA 25 g MMA 25 g MMA 25 g MMA 25 g IBA 25 g MMA 25 g MMA 25 g EMA 25 gMMA Crosslinker: None 5 g 5 g 5 g 5 g 5 g 5 g None 5 g 5 g PEG (400)diacrylate Conductance 1.0 3.4 2.4 3.8 44 2.5 2.8 4.5 1.7 (picomho/cm)Particle Size 255 nm 290 nm 300 nm 240 nm 240 nm 280 nm 300 nm 300 nm260 nm (distribution) (narrow) (narrow) (narrow) (narrow) (narrow)(narrow) (narrow) (narrow) (narrow)

Synthesis of Very Fine Non-Film Forming White Acrylic Latex Particles bySeed Method

A latex of very fine white (non-dye-bearing) acrylic particles,designated L16, was synthesized using the seed method describedfollowing.

2.5 g of FMD-1 and 2.5 g methylstyrene (a mixture of 3- and 4-methylisomers obtained from Aldrich Chemical Company, Milwaukee, Wis., Cat.No. 30,898-6) were added to 250 ml of Fluorinert™ solvent FC-75, in athree-neck flask equipped with a reflux condenser, nitrogen inlet tubeand addition funnel. One gram of the polymerization initiator, Trigonox™21C-50, was added. This reaction mixture was flushed with nitrogen for15 minutes and then the mixture was polymerized for about 100 minutes at80° C. with vigorous stirring using a magnetic stir bar. A white turbidsuspension of seed polymer particles resulted. The temperature of thereaction mixture was lowered to 70° C. with continued stirring andanother 1 part Trigonox™ 21C-50 was added. An additional 10 g of themethylstyrene was added dropwise via an addition funnel into the stirredreaction mixture over a period of 2 hours while the reaction temperaturewas kept at 70° C. After addition of monomer was complete thepolymerization was allowed to continue for another 16 hours. Theresulting latex was then filtered through a thickly folded cheese clothto remove agglomerated particles. The latex had an average particle sizeof 220 nm and a conductance of 0.1 picomho/cm, measured as describedabove.

Synthesis of Very Fine Non-Film Forming Dye-Bearing Acrylic LatexParticles by Seed Method

The synthesis of L16, preceding, was repeated except that 0.15 g ofSolvent Blue (C.I. 97) dye were dissolved in the 10 g of methylstyrenemonomer added dropwise to the seed suspension. The resulting cyancolored latex, designated L17 (Cyan), had an average particle size of375 nm; and a conductance of 0.1 picomho/cm, measured as describedabove.

Additional Synthesis of Very Fine Non-Film Forming Dye-Bearing AcrylicLatex Particles by Seed Method

The synthesis of very fine dye-bearing latex L18 (Cyan), using the seedmethod described following, was repeated three times.

In a reaction flask, 7.5 g of FMD-1 and 2.5 g ethyl acrylate were addedto 250 parts ml of Fluorinert™ solvent FC-75, in a three-neck flaskequipped with a reflux condenser, nitrogen inlet tube and additionfunnel. One gram of the polymerization initiator, Trigonox™ 21C-50, wasadded. This reaction mixture was flushed with nitrogen for 30-45minutes. The temperature was rapidly raised to 80° C. and then themixture was polymerized for 2 hrs with vigorous stirring using amagnetic stir bar. After two hours, a mixture of 10 g of isobornylacrylate and 0.2 g of Solvent Blue (C.I. 97) dye was added dropwise viaan addition funnel into the stirred reaction mixture over a period of 1hour while the reaction temperature was kept at 70° C. An additional 1 gof Trigonox™ 21C-50 was added. After addition of monomer was completethe polymerization was allowed to continue for another 16-20 hours. Theresulting latex was then filtered through a thickly folded cheese clothto remove agglomerated particles. Particle size and conductance weremeasured as described above. In three repetitions of this synthesis, thethree resulting latexes were found to have average particle sizes of140, 160 and 175 nm respectively. Conductance was measured as 0.79picomho/cm for one of the L18 (Cyan) latexes.

Synthesis of Perfluoropolyether Fluoromacromer Disnersant

A fluoromacromer dispersant designated FMD-5 based on aperfluoropolyether was synthesized as follows.

The perfluoroether diol HO—CH₂CF₂—O—(CF₂CF₂O)_(n)—CF₂CH₂—OH wassynthesized, where n is a distribution (nominally 10) and the diol hasan average molecular weight of 1250. Polyethylene glycol (ave. m.w.600)(Aldrich Chemical Co., Milwaukee, Wis.) was mixed with approximatelytwo equivalents of CH₃C(O)Cl at ambient temperature in the presence oftwo equivalents of triethylamine to form a diacetate. The diacetate wasthen fluorinated by direct fluorination, such as disclosed in U.S. Pat.No. 4,523,039 (Lagow et al.). The resulting fluorinated acetate wasmixed with excess amount of methanol whereupon it reacted to give methylesters such as CH₃O(CO)CF₂O—(CF₂CF₂O)_(n−2)—CF₂(CO)OCH₃. These methylesters were then reduced to the corresponding dihydroalcohols, such asHOCH₂CF₂O—(CF₂CF₂O)_(n−2)—CF₂CH₂OH, by reaction with approximately twoequivalents of NaBH₄. The resulting mixture was distilled under reducedpressure and a 1250 m.w. fraction collected.

To 35 g of this perfluoroether diol (m.w. 1250) in a covered amber jarwas added dropwise 4.34 g (aprox. 1 equivalent) of isocyanatoethylmethacrylate (m.w. 155) to obtain a milky liquid. When the milky liquidturned clear, indicating the completion of the reaction between thehydroxyl and isocyanate, two drops of dibutyltin dilaurate were added tothe reaction mixture.

Synthesis of Acrylic Latex Particles Using FMD-5 PerfluoropolyetherFluoromacromer

Acrylic latexes designated L19 (Cyan) and L20 (Near-White) weresynthesized as follows.

For L19(Cyan), 5 g of FMD-5 was combined with 12.5 g methylstyrene (amixture of 3- and 4-methyl isomers obtained from Aldrich ChemicalCompany, Milwaukee, Wis., Cat. No. 30,898-6), 5 g of Gensolve™ 2000, 0.2g Solvent Blue (C.I. 97) and 250 g of Fluorinert™ solvent FC-75, in athree-neck flask equipped with a reflux condenser, nitrogen inlet tubeand addition funnel. A polymerization initiator, Trigonox™ 21C-50, wasadded in the amount of 1 g. This reaction mixture was flushed withnitrogen for 30 minutes and then the mixture was polymerized for 6 hrsat 75° C. A second increment of the initiator in the same amount wasadded and the mixture was polymerized for another 20 hrs at 75° C. Theresulting latex was then filtered through a thickly folded cheese clothto remove agglomerated particles.

The resulting cyan colored latex, designated L19 (Cyan), had an averageparticle size of 172 nm, measured as described above.

For L20 (Near-White), the same procedure was followed except that thecyan dye was replaced with 0.2 g of Magenta Solvent Dye (CAS58559-02-7). The resulting latex, designated L20 (Near-White), was anear-white pale pink color and had an average particle size of 170 nm,measured as described above.

Both L19 (Cyan) and L20 (Near-White) are observed to benon-film-forming.

Various modifications and alterations of this invention will becomeapparent to those skilled in the art without departing from the scopeand principles of this invention, and it should be understood that thisinvention is not to be unduly limited to the illustrative embodimentsset forth hereinabove. All publications and patents are hereinincorporated by reference to the same extent as if each individualpublication or patent was specifically and individually indicated to beincorporated by reference.

We claim:
 1. A latex comprising: a. a highly fluorinated liquid solvent;and b. dispersed particles comprising a polymer comprising unitsaccording to formula I:

wherein each (fcp) is independently selected from highly fluorinatedpolymer chains which optionally terminate at the —A═ group of anotherunit according to formula I; wherein each Q is independently selectedfrom —H and (hcp), wherein no more than one Q of each unit according toformula I may be —H, and wherein each (hcp) is independently selectedfrom straight or branched non-fluorinated polymer chains whichoptionally terminate at the —A═ group of another unit according toformula I; and wherein said latex is non-film-forming.
 2. The latexaccording to claim 1 wherein —A═ is the moiety according to formula II:

wherein each R¹ is independently selected from —H, —CH₃, —F and —Cl; andwherein each R⁶ is independently selected from substituted orunsubstituted C1-C10 alkyl, cyclic alkyl, or aryl groups.
 3. The latexaccording to claim 1 wherein at least one (hcp) comprises a reacting dyeincluded by polymerization.
 4. The latex according to claim 1 whereinsaid particles additionally comprise one or more non-reacting dyes, saidnon-reacting dyes not having a free-radically-polymerizable group. 5.The latex according to claim 1 wherein said particles additionallycomprise a charging agent.
 6. The latex according to claim 5 whereinsaid charging agent is 1-ethyl-3-methyl-1H-imidazoliumbis(trifluoromethylsulfonylamide).
 7. The latex according to claim 1wherein each (hcp) comprises units derived from species selected fromthe group consisting of: alkyl (meth)acrylate monomers andpoly(meth)acrylate crosslinkers.
 8. The latex according to claim 1wherein each (fcp) is selected from: a) fluoropolymer chains comprisingunits according to formula III:

wherein each R¹ is independently selected from —H, —CH₃, —F and —Cl;wherein each n is independently selected from integers from 1 to 10;wherein each R² is selected independently from: highly fluorinatedsubstituted or unsubstituted C1-C20 alkyl, cyclic alkyl, or aryl groups;—N(R³)SO₂R⁴, wherein each R³ is selected independently from —H andsubstituted or unsubstituted C1-C8 alkyl, and wherein each R⁴ isselected independently from highly fluorinated substituted orunsubstituted C1-C20 alkyl, cyclic alkyl, or aryl groups; and b)fluoropolymer chains comprising —(CF₂)_(a)CFXO— units, wherein each a isindependently selected from 0-3 and wherein each X is independentlyselected from —F, —CF₃ or —CF₂CF₃.
 9. The latex according to claim 1wherein said particles have an average diameter of 1000 nm or less. 10.The latex according to claim 1 wherein said particles have an averagediameter of 350 nm or less.
 11. The latex according to claim 1 whereinsaid particles have an average diameter of 300 nm or less.
 12. The latexaccording to claim 1 wherein said particles have an average diameter of250 nm or less.
 13. The latex according to claim 1 wherein saidparticles have an average diameter of 200 nm or less.
 14. A latexcomprising: a. a highly fluorinated liquid solvent; and b. dispersedparticles comprising a polymer which is the polymerization product of amixture comprising: i. 40-99 percent by weight of one or morenon-fluorinated free-radically-polymerizable monomers, ii. 1-60 percentby weight of one or more highly fluorinated macromers terminated at oneor more sites with free-radically-polymerizable groups, iii. 0-35percent by weight of one or more crosslinkers having two or morefree-radically-polymerizable groups, and iv. 0-25 percent by weight ofone or more reacting dyes bearing a free-radically-polymerizable group;wherein said latex is non-film-forming.
 15. The latex according to claim14 wherein said particles additionally comprise one or more non-reactingdyes, said non-reacting dyes not having a free-radically-polymerizablegroup.
 16. The latex according to claim 14 wherein said particlesadditionally comprise a charging agent.
 17. The latex according to claim16 wherein said charging agent is 1-ethyl-3-methyl-1H-imidazoliumbis(trifluoromethylsulfonylamide).
 18. The latex according to claim 14wherein said non-fluorinated free-radically polymerizable monomers areselected from (meth)acrylate monomers.
 19. The latex according to claim14 wherein said polymer is the polymerization product of a mixturecomprising 60-99 percent by weight of said one or more non-fluorinatedfree-radically-polymerizable monomers.
 20. The latex according to claim14 wherein said highly fluorinated macromers are selected from macromersaccording to Formula IV:

wherein each R¹ is independently selected from —H, —CH₃, —F and —Cl;wherein each R⁶ is independently selected from substituted orunsubstituted C1-C10 alkyl, cyclic alkyl, or aryl groups, wherein each(fcp) is selected independently from: a) fluoropolymer chains comprisingunits according to formula V:

wherein each R¹ is independently selected from —H, —CH₃, —F and —Cl;wherein each n is independently selected from integers from 1 to 10;wherein each R² is selected independently from: highly fluorinatedsubstituted or unsubstituted C1-C20 alkyl, cyclic alkyl, or aryl groups;—N(R³)SO₂R⁴, wherein each R³ is selected independently from —H andsubstituted or unsubstituted C1-C8 alkyl, and wherein each R⁴ isselected independently from highly fluorinated substituted orunsubstituted C1-C20 alkyl, cyclic alkyl, or aryl groups; and b)fluoropolymer chains comprising —(CF₂)_(a)CFXO— units, wherein each a isindependently selected from 0-3 and wherein each X is independentlyselected from —F, —CF₃ or —CF₂CF₃; wherein each (fcp) optionallyterminates in another unit according to formula IV above.
 21. The latexaccording to claim 20 wherein said polymer is the polymerization productof a mixture comprising 1-40 percent by weight of said one or morehighly fluorinated macromers terminated at one or more sites withfree-radically-polymerizable groups.
 22. The latex according to claim 20wherein said polymer is the polymerization product of a mixturecomprising 1-10 percent by weight of said one or more highly fluorinatedmacromers terminated at one or more sites withfree-radically-polymerizable groups.
 23. The latex according to claim 14wherein said polymer is the polymerization product of a mixturecomprising at least 0.1 percent by weight of said crosslinkers.
 24. Thelatex according to claim 14 wherein said particles have an averagediameter of 1000 nm or less.
 25. The latex according to claim 14 whereinsaid particles have an average diameter of 350 nm or less.
 26. The latexaccording to claim 14 wherein said particles have an average diameter of300 nm or less.
 27. The latex according to claim 14 wherein saidparticles have an average diameter of 250 nm or less.
 28. The latexaccording to claim 14 wherein said particles have an average diameter of200 nm or less.
 29. An electrophoretic display comprising the latexaccording to claim 1, wherein said dispersed particles may bealternately a) removed from dispersion by application of an electricfield, and b) redispersed by removal or reversal of said electric field.30. An electrophoretic display comprising the latex according to claim2, wherein said dispersed particles may be alternately a) removed fromdispersion by application of an electric field, and b) redispersed byremoval or reversal of said electric field.
 31. An electrophoreticdisplay comprising the latex according to claim 14, wherein saiddispersed particles may be alternately a) removed from dispersion byapplication of an electric field, and b) redispersed by removal orreversal of said electric field.
 32. An electrophoretic displaycomprising the latex according to claim 20, wherein said dispersedparticles may be alternately a) removed from dispersion by applicationof an electric field, and b) redispersed by removal or reversal of saidelectric field.
 33. The latex according to claim 1 wherein (fcp) isselected from fluoropolymer chains comprising —CF₂CF₂O— units.
 34. Thelatex according to claim 14 wherein said highly fluorinated macromersare selected from macromers according to Formula IV:

wherein each R¹ is independently selected from —H, —CH₃, —F and —Cl;wherein each R⁶ is independently selected from substituted orunsubstituted C1-C10 alkyl, cyclic alkyl, or aryl groups, wherein each(fcp) is selected independently from fluoropolymer chains comprising—CF₂CF₂O— units, and wherein each (fcp) optionally terminates in anotherunit according to formula IV above.